Four quadrant biopsies in regular ranges is the goldstandard in monitoring this disease. The ideal situation for the endoscopist is to visualize cellular structures, which implies having microscopic imaging available. A potential candidate to fill this gap could be confocal fluorescence microscopy (Cellvizio®-GI and Mauna Kea Technologies). To compare the gold standard with the confocal fluorescence microscopy for detection of metaplastic - or intraepithelial neoplastic changes of barrett-suspicious esophageal mucosa this study has been initiated.

Inclusion Criteria:

• age between 18 and 80 years
• regular esophagogastroduodenoscopy for patients with known barrett esophagus (at least stadium C0M1)
• patients presenting for endoscopic mucosectomy with intraepithelial neoplastic changes <1cm
• patients presenting with suspected intraepithelial neoplastic changes
• patients receiving acid suppressive therapy in standard dose for at least 4 weeks

Exclusion Criteria:

• no informed consent
• thrombocytopenia, quick <50%, PTT >50 sec
• patients with coronary heart disease or existent valve plasties
• women with potential pregnancy
• patients with chronic renal failure
• patients with allergies
• patients with chronic obstructive pulmonary disease